Tor Switch L2 Or L3 ?

[munnavai]

Hi,

I am newbie, i am trying to understand the physical networking required for VTEP.

- if Tor switch is L2 then it is easy to think Each VTEP Interface will get an IP from the same subnet, Pool for Example 192.168.100.10 - 192.168.100.20.
- But, if the Tor Switch is L3 then its Each port will act as a gateway / Router port, each port with different subnet. How do i Define the Pool here ?
i am confused here, each Vtep with Different Subnet ?

Please help me on this.

[Sree]

Well if you have routed design at TOR just ensure that you have unique subnet per VTEP Pool and VLAN remains the same which will ease configuration and support related issues.  If you have a common IP fabric stretched across the PODS , that will again fall under same approach. Also ESXI hosts that are connected to same VDS, the VLAN ID for the VTEPs and the NIC teaming must be the same.

https://www.vmware.com/content/dam/digitalmarketing/vmware/en/pdf/products/nsx/vmw-nsx-network-virtualization-design-gui…  ( Page : 104) 

[munnavai]

Hi,

Thanks a Lot for your response,

can you please verify my understanding after you say "ESXI hosts that are connected to same VDS, the VLAN ID for the VTEPs and the NIC teaming must be the same"

Say, we are in Rack1, Switch: Leaf1, Port 1-3 (for 3 VTEP)

Port1 IP: 192.168.10.254

Port2 IP: 192.168.20.254

Port3 IP: 192.168.30.254

ESXi1 -> VTEP IP -> 192.168.10.1 (Gateway:192.168.10.254) -> Vlan50 (Connecting to) Leaf1:Port1

ESXi2 -> VTEP IP -> 192.168.20.1 (Gateway:192.168.20.254) -> Vlan50 (Connecting to) Leaf1:Port2

ESXi3 -> VTEP IP -> 192.168.30.1 (Gateway:192.168.30.254) -> Vlan50 (Connecting to) Leaf1:Port3

am i correct upto this ?

Thanks

[Sree]

ESXi1 -> VTEP IP -> 192.168.10.1 (Gateway:192.168.10.254) -> Vlan50 (Connecting to) Leaf1:Port1

ESXi2 -> VTEP IP -> 192.168.20.1 (Gateway:192.168.20.254) -> Vlan50 (Connecting to) Leaf1:Port2

ESXi3 -> VTEP IP -> 192.168.30.1 (Gateway:192.168.30.254) -> Vlan50 (Connecting to) Leaf1:Port3

Why do you need three Pools in same rack ?  Are these hosts part of same cluster ?  If your understanding is -> Three VTEPS needs three different subnets in all the designs ,that is not correct.  If your transport zone is extended across multiple RACKS/PODS we need same VLAN-ID for VTEPS which are part of different subnets  and the underlay can be L3 or under a common IP fabric ( Like ACI) . If this is a single RACK design , i would keep one subnet for VTEP with unicast mode replication.

[munnavai]

Hi Sreec,

Thanks a Lot to be with me, i am really not getting the L3 Underlay Design, Lets think 3 ESXi, Same Cluster, Same Transport Zone.

when ESXi connected to L2 Switch, we define a Pool Of IP, From which these VTEP's are getting same subnet IP and Communicating with each other freely without any Routing.

But, when these ESXi's are connected to a L3 Switch, i am thinking Each L3 Switch port must be of different Subnet as like Router.

If L3 Ports needs different subnet, then how can i define pool for 3 Vtep ? I am thinking to connect to L3 Each port Vtep must need Different subnet,

Please give me a simplest picture how can i connect these 3 ESXi to L3 Each Port, it will clear my head.

Thanks.

[Sree]

I understand your question , but i'm curios to know why you need three VTEP pools for three hosts which are part of same cluster ?  Why your network design is demanding three pools ?  Ideally you should place it under a single pool and L3 being terminated at SVI side.

[munnavai]

Hi,

Thanks.

I don't need 3 pool, i just want to understand this, This image opens my mind a little. but still complex for me.

so, my each esxi Vtep Interface can be assigned a different subnet ip with same vlan ID, and it will terminate at 3 SVI Port which are of same vlan. this is clear now,

But how can i define a single IP Pool of 3 different subnet ? or i have to create 3 ip pool for each subnet to be taken by each VTEP interface ?

Thanks

[Sree]

But how can i define a single IP Pool of 3 different subnet ? or i have to create 3 ip pool for each subnet to be taken by each VTEP interface ?

Yes , in this case you need three NSX IP Pools with unique Subnet. If you prefer DHCP you should read this thread ->how to assign different VTEP subnet for each rack from one cluster pool?